Gutteridge S
Central Research and Development Department, Du Pont Company, Wilmington, Delaware 19880-0402.
J Biol Chem. 1991 Apr 25;266(12):7359-62.
The relative specificities of the carboxylase and oxygenase reactions catalyzed by the recombinant large subunit core (L8) of Synechococcus ribulose 1,5-bisphosphate carboxylase have been determined. The L8 core still retained the ability to catalyze both reactions but at a much reduced turnover rate, about 0.6% of the holoenzyme. The fate of ribulose 1,5-bisphosphate during carboxylation and oxygenation by L8 was compared with the Synechococcus holoenzyme (reconstituted from L8 and recombinant small subunits), the carboxylase from Rhodospirullum rubrum, and that of spinach. The absence of small subunits had no significant effect on the partitioning of the bisphosphate substrate between the two reactions. Thus the course of the two competing reactions is a characteristic of the structural elements that compose the L-subunits, whereas the S-subunits exert their effect on factors common to both reactions such as the specificity of the bisphosphate substrate.
已测定了由集胞藻1,5-二磷酸核酮糖羧化酶的重组大亚基核心（L8）催化的羧化酶反应和加氧酶反应的相对特异性。L8核心仍保留催化这两种反应的能力，但周转速率大幅降低，约为全酶的0.6%。将L8在羧化和加氧过程中1,5-二磷酸核酮糖的去向与集胞藻全酶（由L8和重组小亚基重构而成）、红螺菌羧化酶以及菠菜羧化酶进行了比较。小亚基的缺失对二磷酸底物在这两种反应之间的分配没有显著影响。因此，这两种竞争反应的进程是构成L亚基的结构元件的特征，而S亚基对两种反应共有的因素如二磷酸底物的特异性发挥作用。
